Timing Of Diapause Termination Research Articles

A Crude Awakening: Effects of Crude Oil on Lipid Metabolism in Calanoid Copepods Terminating Diapause.

Calanus finmarchicus and Calanus glacialis are keystone zooplankton species in North Atlantic and Arctic marine ecosystems because they form a link in the trophic transfer of nutritious lipids from phytoplankton to predators on higher trophic levels. These calanoid copepods spend several months of the year in deep waters in a dormant state called diapause, after which they emerge in surface waters to feed and reproduce during the spring phytoplankton bloom. Disruption of diapause timing could have dramatic consequences for marine ecosystems. In the present study, Calanus C5 copepodites were collected in a Norwegian fjord during diapause and were subsequently experimentally exposed to the water-soluble fraction of a naphthenic North Sea crude oil during diapause termination. The copepods were sampled repeatedly while progressing toward adulthood and were analyzed for utilization of lipid stores and for differential expression of genes involved in lipid metabolism. Our results indicate that water-soluble fraction exposure led to a temporary pause in lipid catabolism, suggested by (i) slower utilization of lipid stores in water-soluble fraction-exposed C5 copepodites and (ii) more genes in the β-oxidation pathway being downregulated in water-soluble fraction-exposed C5 copepodites than in the control C5 copepodites. Because lipid content and/or composition may be an important trigger for termination of diapause, our results imply that the timing of diapause termination and subsequent migration to the surface may be delayed if copepods are exposed to oil pollution during diapause or diapause termination. This delay could have detrimental effects on ecosystem dynamics.

Time of Diapause Termination in the Pistachio Seed Wasp Eurytomα plotnikovi (Hymenoptera: Eurytomidae) ίη Northem Greece and Under Certain Photoperiods and Temperatures

Mummified pistachios containing fully grown diapause larvae of Eurytoma plotnikovi Nikol’skaya were collected from mid-November on from trees in coastal northern Greece and placed in a field cage. Every 5 weeks, fruits from the cage and from the trees were placed at 16L:8D h and 26°C. Pupation within I or 2 weeks showed that diapause was terminated between early April and early May. Two years later, strarting in early September, mummified fruits from the same trees were collected at bimonthly intervals and subjected fora few to several months to combinations of certain temperatures and photoperiods, followed by different conbinations of temperatures and photoperiods, then to 16L:8D h and 25°C. In larvae of early September, 6 months at 6°C was the most effective treatment for diapause termination. Diapause was also terminated or almost so after: (1) 4 months at 25°C and long photophase followed by 5 months at 14° or 6°C, (2) 4 months at 20°C and a 12 h photophase followed by 3 months at 14° or 6°C, (3) 4 months at WC and short photophase followed by 3 months at 6°C, and (4) 4 or 6 months at WC and short photophase. The results are in line with previous work, showing that, in larvae picked in early autumn, low temperatures and short days fora few to several months followed by high temperatures and a long day favor an early and synchronous termination of diapause. The time of diapause termination being in mid-spring, long days seem to be a reasonable signal for diapause termination, as shown by previous work. In larvae of early January, for a synchronous diapause termination four months at 20°C and a 12 h photophase followed by 3 months at WC and an 8 h photophase was the most effective treatment, without the need for a long-day final condition.

Assessing hatching rates and the timing of hatching from plankton resting stages-an accurate and cost effective high throughput approach

Hatching rates and the timing of diapause termination are traits of high relevance in ecology and evolution of diapausing organisms. The analysis of hatching from dormant stages of planktonic organisms is an active area of research, which has been extensively studied in the context of phenology adjustment over latitude. Research on populations from temporary ponds has revealed temporal hatching profiles consisting of various hatching peaks, which is considered a risk-spreading strategy. Studies on outstanding scientific questions such as the evolution of risk-spreading strategies, the importance of genetic variation in hatching in an eco-evolutionary context, and the genomic underpinning of hatching phenotypes all require very large sample sizes. We therefore developed a high throughput approach for the assessment of hatching rates and temporal hatching profiles of resting stages from crustacean zooplankton. Our method consists in the photographic monitoring of resting stages hatching assays and the detection of hatchlings using free software for the automation of biological image analysis. We compared the performance of our new method with data obtained by traditional visual assessment of hatching. Our results indicate that our approach is highly accurate (>95%) and raises efficiency by a factor of 10 compared to non-automated visual assessment. Our new high throughput approach therefore allows to upscale the analysis of temporal hatching profiles and hatching success to sample sizes that will enable large-scale genomic studies or massive phenotyping and monitoring of these highly relevant traits in the future.

Imidazole derivative KK-42 boosts pupal diapause incidence and delays diapause termination in several insect species

The imidazole derivative KK-42 is a synthetic insect growth regulator known previously to be capable of averting embryonic diapause in several Lepidoptera, but whether it also affects diapauses occurring in other developmental stages remains unknown. In the present study, we examined the effect of KK-42 on pupal diapause in two species of Lepidoptera, the Chinese oak silkworm Antheraea pernyi and the corn earworm Helicoverpa zea, and in one species of Diptera, the flesh fly Sarcophaga crassipalpis. In A. pernyi, KK-42 delayed pupal diapause termination under the long day conditions that normally break diapause in this species. Likewise, in H. zea, KK-42 delayed termination of pupal diapause, a diapause that, in this species, is normally broken by high temperature. KK-42-treated pupae of these two species eventually terminated diapause and successfully emerged as adults, but the timing of diapause termination was significantly delayed. KK-42 also significantly increased the incidence of pupal diapause in H. zea and S. crassipalpis when administered to larvae that were environmentally programmed for diapause, but it was not capable of inducing pupal diapause in H. zea if larvae were reared under environmental conditions that do not normally evoke the diapause response. Experiments with H. zea showed that the effect of KK-42 on pupal diapause was dose- and stage-dependent, but not temperature-dependent. Results presented here are consistent with a link between KK-42 and the ecdysteroid signaling pathway that regulates pupal diapause.

Diapause Specific Expressed Sequence Tags of Antheraea mylitta Drury

Daba bivoltine ecorace of tropical tasar silkworm Antheraea mylitta Drury undergoes facultative pupal diapause and shows different type of voltinism. During course of its long pupal diapause, erratic, unseasonal and unsynchronised emergence of adults is noticed and losses of seed stock range in between 10 - 30%. In order to avoid all these problems, proper understanding of induction, maintenance and termination state of diapause of this economically important insect is felt essential. The presence of diapause specific expressed sequence tags (ESTs) through PCR clones of Hsp70, Hsp23, hexamerins and PCNA genes have been reported in the present study. The ESTs obtained form the primers of Hexamerins were only seen when pupae were 65 and 165 days old. ESTSs obtained form the primers designed form Hsps 70 sequences were up regulated during early (D0), middle (D75) and late age (D135 to D165) of diapause period. The presence of Hsp23 was obtained during preparatory phase of diapause (IV instar) and pupae of early and mid aged diapause period (D0 to D75) and late age of diapause (D135 to D165). ESTs of Hsp22 were seen during preparatory phase of diapause (IV&V instar), throughout diapause period and even after diapause period was over. ESTs of Hsps90 were seen during preparatory stage (IV instar) and middle and late age of diapause period. Est of PCNA were down regulated throughout diapause period, their up regulation was seen at the time of diapause termination. Another group of ESTs obtained from different sets of Hsps 70 primers were up regulated intermittently through out the diapause period. Hsps90 were upregulated during middle and late age of true diapause period. At the fag end of true diapause period, ESTs disappeared when pupae became older than 165 days as no ESTs were seen when pupae were 195 days old indicating the actual age of diapause termination. It was also evidenced by the up regulation of PCNA.ESTs whose concentration remained very low through out the diapause period but its intensity increased at 195 days which further increased at 210 days. The pupae of Daba BV of 195 days and older can be further exploited for low temperature treatment to delay the moth emergence in adverse summer season so as to produce dfls matching with the actual cropping schedule.

Juvenile hormone titer and advertised quality are associated with timing of early spring activity in Polistes dominulus foundresses

Timing of diapause termination has an important influence on individual reproductive success, but relatively little research has explored how individuals differ in their response to diapause termination cues. We tested individual variation in the timing of post-diapause activity in Polistes dominulus paper wasps. Wasps were overwintered in a temperature-controlled chamber. In the spring, ambient temperature was gradually increased and the time each foundress became active was recorded. Timing of post-diapause activity was most strongly associated with the facial patterns that function as a conventional signal of quality. Foundresses with facial patterns indicating high quality became active at lower temperatures than individuals with facial patterns indicating low quality. Early diapause termination is associated with dominance, so the relationship between diapause termination and facial patterns provides a mechanism linking facial patterns with dominance. Body weight and mating status did not influence timing of post-diapause activity. Juvenile hormone (JH) titer at the time of diapause termination was also measured in a subset of foundresses. There was no JH titer threshold for diapause termination. Instead, our results suggest that individuals may have different threshold responses to JH, as individuals that became active at a lower temperature had lower JH titers than individuals that became active at a higher temperature. Overall, there is substantial individual variation in response to diapause termination cues and the variation is likely to have important impacts on the fitness of nest-founding females.

Shelf recruitment of Calanus finmarchicus off the west coast of Norway: role of physical processes and timing of diapause termination

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 386:163-180 (2009) - DOI: https://doi.org/10.3354/meps08060 Shelf recruitment of Calanus finmarchicus off the west coast of Norway: role of physical processes and timing of diapause termination Annette Samuelsen1,*, Geir Huse2, Cecilie Hansen1 1Nansen Environmental Remote Sensing Center, Thormoehlensgate 47, 5006 Bergen, Norway 2Institute of Marine Research, Box 1870, Nordnes, 5817 Bergen, Norway *Email: annette.samuelsen@nersc.no ABSTRACT: The copepod Calanus finmarchicus is an important part of the Norwegian Sea ecosystem because of its dominating abundance and importance as prey for fish larvae and adult planktivorous fish. The abundance of C. finmarchicus on the Norwegian shelf is generally low in winter, whereas in spring the shelf is replenished by individuals that overwinter at depth, either in fjords or in the deep basins of the Norwegian Sea. In the present study shelf recruitment is investigated using an individual-based model for C. finmarchicus coupled to the HYbrid Coordinate Ocean Model and a biophysical model. The model was set up on a nested grid along the west coast of Norway and used to study the shelf recruitment originating from the Norwegian Sea. We investigate the effect of wind, currents and the timing of Calanus ascent on the shelf abundance of C. finmarchicus. The most important findings are the following: (1) periods of large on-shelf transport are connected with strong westerly winds associated with passing low-pressure systems; (2) the transport of overwintering adults onto the shelf determines the total shelf abundance prior to mid-summer; (3) the early spring bloom on the shelf causes increased shelf population of C. finmarchicus in the spring and throughout the summer compared to the areas further off-shore; and (4) the entry routes taken by C. finmarchicus are related to bathymetry; in particular, the deep trenches around Halten Bank and the Norwegian trench are favoured places to enter the Norwegian shelf. KEY WORDS: Cross-shelf transport · Calanus · Diapause · Norwegian Sea · Herring recruitment Full text in pdf format PreviousNextCite this article as: Samuelsen A, Huse G, Hansen C (2009) Shelf recruitment of Calanus finmarchicus off the west coast of Norway: role of physical processes and timing of diapause termination. Mar Ecol Prog Ser 386:163-180. https://doi.org/10.3354/meps08060 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 386. Online publication date: July 02, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

Dry season survival, diapause duration and timing of diapause termination in the millet stem borer, Coniesta ignefusalis (Hampson) (Lepidoptera: Pyralidae) in Northern Ghana

Studies were conducted between 1996 and 1997 in Northern Ghana on the dry season survival tactics of the millet stem borer Coniesta ignefusalis (Hampson). Results confirmed that the main survival tactic employed by the insect was larval diapause, which lasts from November to May the following year. In both years, diapause termination occurred in the field 4-6 weeks after the resumption of the rains, depending on the year and location. Larval mortality rate was high during diapause with peaks occurring towards the end of the dry season in May. During the 2 years, larval populations declined by at least 50% between the start of diapause and its termination. No parasitoids were encountered during the study period, suggesting that biocontrol agents are probably not very important in the population dynamics of the insect. The implications of these findings for management of the pest are discussed.

DIAPAUSE TERMINATION AND THE THERMAL REQUIREMENTS FOR POSTDIAPAUSE DEVELOPMENT IN SIX ONTARIO POPULATIONS OF THE SPOTTED TENTIFORM LEAFMINER, PHYLLONORYCTER BLANCARDELLA (LEPIDOPTERA: GRACILLARIIDAE)

AbstractThe timing of diapause termination and the thermal characteristics of postdiapause development were compared in six Ontario populations of the spotted tentiform leafminer, Phyllonorycter blancardella (Fabr.). The populations studied were from the major apple growing areas which are located in four climatically different zones. Pupae of all populations collected in the fall and stored under simulated overwintering conditions had terminated diapause by the end of January. Pupae overwintering under natural conditions had also terminated diapause by this time. Significant population differences occurred in the postdiapause developmental threshold (t0) and thermal constant (K). Simulating postdiapause development and emergence of the six populations using the 1981 temperature records from one location resulted in a 9-day difference between the earliest and latest mean emergence times. The implications of these results for pest management are discussed.

Environmental Control of the Seasonal Life Cycle of Adalia bipunctata (Coleoptera: Coccinellidae)

Adalia bipunctata L. has low developmental thresholds ( t ) for postdiapause and nondiapause development that adapt it to activity early in the season. Postdiapause reproductive development leading to oviposition requires an accumulation of 87 degree-days ( K ) above a relatively low developmental threshold temperature ( t ) of 6.8°C. Overwintering adults disperse and initiate oviposition during early to mid-May. The linearly derived ( t ) and ( K ) values of 263 ± 9.0 degree-days above 9.0°C for preimaginal development and daily maximum-minimum temperatures from outdoors accurately predicted outdoor developmental rates. Preimaginal development outdoors during June and July required 269 ± 12 degree-days above 9.0°C under conditions of excess prey. In the field, there are two to three generations per year in the Ithaca, N.Y., area. The critical photoperiod for diapause induction in the Ithaca, N.Y., (~42°N) population lies between LD 13:11 and LD 14:10 (23°C). Short daylengths maintain diapause, and during autumn the duration of diapause is quantitatively related to photoperiod. Diapause completion does not require chilling: during winter-early spring. photoperiod may exert some influence on the timing of diapause termination.

暖地におけるナミハダニ休眠雌の出現時間及びその個体群の産卵時間

The two-spotted spider mite, Tetranychus urticae KOCH, was collected from four localities in Japan; Morioka, Shizuoka, Tottori, and Kumamoto. Laboratory experiments were conducted in Hiroshima and Kumamoto in 1976 and 1977, respectively. The time of the first oviposition by diapause terminated females in the field was recorded in Kumamoto in the spring of 1978. The emergence time of diapause females differed distinctly among three of the local stocks. The Shizuoka stock had no diapause despite the fact that the same environmental conditions were given to all stocks. The time of entering diapause was the earliest in the highest latitude Morioka stock and latest in the lowest latitude Kumamoto stock. The Tottori stock ranked in the medium position. The time of diapause termination also differed among these stocks. It seems that the females from the eggs laid in mid- to late October begin to enter diapause in the case of normal climatic conditions. However, if warm winter prevails, nondiapause females are able to survive and ovinosit successively during winter.

Influence of Genetic Selection on Diapause Termination of the Pink Boll worm1, 2, 3

Investigations were conducted to determine if diapausetermination of the pink bollworm, Pectinophora gossypiella (Saunders), involves inherited characteristics. A 2-way selection was performed on a natural-diapausing population; the 1st larvae to terminate diapause composed an “early-pupating line” while the last larvae to terminate comprised a “late-pupating line.” Six and 5 generations were observed from the early- and late-pupating lines, respectively. The early-pupating line remained unchanged until the 5th generation and all generations terminated significantly earlier than those of the late line which was progressively later in terminating diapause with the longest termination time occurring in the 5th generation. Reciprocal crosses between the 2 lines indicated no dominance of either termination time. Sex-linkage was indicated, however, because the early-female × late-male cross-terminated significantly later than its reciprocal. Diapause termination appeared to be under genetic control in that the time of parental diapause termination influenced the time of diapause termination in the progeny. Consistency in the time of diapause termination in the early-pupating line indicated homogeneity of this characteristic. Conversely, the observed diversity in the time of diapause termination in the late individuals indicated a heterogeneous population.

Rates and cycles of oxygen consumption during pupal diapause in Sarcophaga flesh flies

The rate of oxygen consumption in non-diapausing flesh flies during the pupal and pharate adult stages follows a U-shaped curve with a minimum of 140 to 150 mm 3/g. per hr at 25°C. In diapausing pupae the mean QO 2 falls to 10 to 20 mm 3/g. per hr. Continuous measurements with single diapausing pupae show that the QO 2 is not constant; cycles of high oxygen consumption occur with a periodicity of several days. The cycle periodicity differs with species and temperature. The time between QO 2 peaks in Sarcophaga crassipalpis is twice as great at 18°C as it is at 25°C. The cycles of high oxygen consumption are close together in early diapause; in mid-diapause the cycles become farther apart, and as the end of diapause is approached the cycles again become closer together. The time of diapause termination appears unrelated to the phase of the QO 2 cycles. Injury produces an increase in the metabolic rate, but an acceleration of diapause termination was not observed.

Termination of Pupal Diapause in the Bollworm12

Diapausing pupae of Heliothis zea (Boddie) were subjected to different photoperiods and temperatures in bioclimatic cabinets, and the number of days required for the termination of diapause was recorded. Termination of diapause in the bollworm was greatly influenced by temperature but not photoperiod, and the number of days for diapause termination was inversely relative to the temperature. Bollworms were reared in an insectary under natural daylengths and prevailing temperatures. All pupae that diapaused were held in the insectary over winter and the time of diapause termination in the spring was related to the occurrence of relatively consistent temperature above 10°C.